1. Field of the Invention
The invention relates to an improved method for decreasing the lost circulation and fluid loss or seepage loss of drilling fluid and to the composition of the drilling fluid with particular additives.
2. Description of the Prior Art
For drilling operations, a drilling mud system is designed as a circulating system with all the fluid retained in the system itself. However, various types of losses do occur during the drilling operation. Some losses occur on the surface due to storage, evaporation and other environmental factors. However, the greatest loss of fluid generally occurs down hole during a drilling operation. These losses can take several different forms. For example, large, gross loss of whole fluid (solids and liquid) is commonly referred to as lost circulation. This occurs when the whole mud seeps into large sand formations and cavities. Lost circulation can be anywhere from 100% to only a partial loss of returns down to 20% or 30%. These losses must be compensated by further addition of expensive drilling mud. It is desirable to avoid further loss of whole mud by use of additives that plug the sands and cavities.
At the other extreme is a loss of only the liquid phase which is generally referred to as fluid loss. This loss occurs as the result of the actual filtration of the solids by the formation due to a differential pressure from the fluid column to the formation. The result is that the non-fluid portion remains in the bore hole. As this occurs, a filter cake forms which, if allowed to build, results in the drill pipe becoming stuck. A generalized category that is referred to as seepage loss occurs when there is a combination of whole loss of fluid coupled with filtration losses. These losses are small but continuous.
Numerous patents address the problem of lost circulation or seepage. Patent literature is replete with examples of various agricultural and cellulosic waste products being used as lost circulation materials and seepage control agents designed to function in specific ways. Yet lost circulation remains a critical issue in the drilling industry often directly affecting the profitability of a well.
Examples of patents addressing this recognized problem include U.S. Pat. No. 5,071,575 and 5,004,553 issued to House for well working compositions using ground oat hulls in a certain particle size range with the possibility of adding one or more agricultural byproducts including ground citrus pulp. Likewise, U.S. Pat. No. 5,147,852 issued to Cowan, discusses the use of cellulose materials generally described as those from wood sources of fibrous materials, indicating generally the benefit of cellulose.
Various agricultural and cellulosic waste products are generally taught for being used as lost circulation materials and seepage control agents. Also, a variety of patents teach different particle size and distribution based on their physical properties. For example U.S. Pat. No. 5,229,018 issued to Forest teaches the use of peanut hulls as an additive along with a suitable suspending agent. Forest identifies the critical elements as being the size of the particles and the percentage of compositions of various naturally occurring compounds. As such, Forest teaches that the peanut hull is particularly useful as a drilling additive.
In spite of the wide body of research and material devoted to solving the problem of fluid loss and seepage control, drilling conditions continue to evolve and improved additives are proactively sought by drilling companies. Some of the currently used additives alter the properties of the drilling fluids, such as viscosity, creating additional problems in operation. Other additives may be useful as lost circulation additives while proving ineffective for controlling fluid loss.
Common additives tend to drastically alter the properties of the drilling fluid. For example, use of certain cellulose materials is known to xe2x80x9cbreakxe2x80x9d emulsions. When this occurs, fluid loss becomes extremely high and other adverse effects occur. This can occur with plasticizers as well. Also, known products generally tend to increase the viscosity of the fluid and add to the colloidal concentration of particles, resulting in decreased penetration rates. This also leads to problems associated with the lubricating characteristics of the drilling fluid. An improved additive is needed to meet the needs of the drilling industry.
It is an object and a goal of this invention to provide an additive that effectively prevents fluid loss, seepage and lost circulation.
It is an object and a goal of this invention to provide an organic additive which, when mixed with drilling fluid, creates a fluid that reduces fluid loss, seepage and lost circulation.
It is an object and a goal of this invention to provide an organic by-product with naturally occurring desirable compounds for improved control of lost circulation, fluid loss and seepage.
It is an object and a goal to use discarded organic material which would otherwise be a waste product.
It is an object and a goal of this invention to provide an organic additive that reduces the need to add further refined chemical components to the system, such as lignosulfonates and tannins.
It is an object of the present invention to provide an additive which is highly effective as a lost circulation and seepage control agent in both water base and oil base well working fluids.
It is an object of the invention to provide an additive which controls seepage loss and lost circulation without adversely affecting the rheology of the system.
It is another object of this invention to provide well working compositions having a low lost circulation or seepage loss.
It is an object of this invention to use the waste product of other industries as a feedsource for the additive.
These and other objects of the invention will appear to one skilled in the art as the description thereof proceeds.
The present invention includes a method of performing drilling operations wherein a drilling fluid is circulated in a well being drilled in the ground comprising the steps of grinding a tannin-containing organic waste to form granules, adding the ground tannin-containing organic waste product to the drilling fluid, and circulating the drilling fluid with the ground tannin-containing organic waste product in the well while drilling operations are being carried out. In a preferred embodiment, tannin-containing organic waste products include grape pomace, tomato pomace, beet pomace, yellow pine bark, yellow pine, wood bark and the like. A pomace, such as tomato, grape or beet, is generally described as the crushed matter remaining of the pressed items. This can contain any combination of pulp, skin, seed or other naturally occurring substance in the pressed item. These organic products can be used individually or in combination.
This invention also encompasses a lost circulation/fluid loss additive for drilling fluid. The lost circulation/fluid loss additive comprises one or more of the following: ground grape pomace, ground tomato pomace, ground yellow pine bark, ground wood bark, ground yellow pine or the like. This additive is useful to control lost circulation, seepage and/or fluid loss.